Research Finds 'New Crop' of Breast Cancer Genes

MONDAY, June 1 (HealthDay News) -- Researchers say they have found a gene common in up to one in five breast cancers that a blood pressure medication might combat.

Their study, published online in this week's issue of the Proceedings of the National Academy of Science, found that the AGTR1 gene makes healthy breast cells act like cancer cells. But tests on mice with tumors containing the gene found that the blood pressure drug losartan (Cozaar) stopped that behavior and shrank the tumors by 30 percent within eight weeks of treatment, according to the researchers, from the University of Michigan Comprehensive Cancer Center.

The blood pressure drug had no effect on tumors lacking the gene.

"We suspect our analysis has uncovered a new crop of potentially important breast cancer genes," study author Dr. Arul Chinnaiyan, a pathology professor at the university's medical school, said in a news release from the school. "What's also exciting is this gene is blocked by a drug that's already available on the market."

In a study of breast tumors, the researchers found that AGTR1 was the second most commonly expressed gene, after ERBB2, which is more commonly known as HER2 and is found in up to 30 percent of all human breast cancers. In fact, AGTR1, which was found in 10 percent to 20 percent of the breast tumors, was found in excess only in tumors that lacked ERBB2 and that expressed the estrogen receptor, known as ER-positive.

"AGTR1 is very analogous to HER2 or ERBB2," said Chinnaiyan, who is also director of the Michigan Center for Translational Pathology. "HER2 is a bona fide treatment target for patients with that type of breast cancer. This research defines a novel subtype of ER-positive breast cancer that we hope can be similarly targeted for treatment."

She also said the findings should lead to a more detailed study of losartan as a treatment for AGTR1-positive breast tumors.